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When you own a big tank, finding a filter can be a bit challenging as you need one that is both powerful and efficient. More often than not, filters aimed for big aquariums lack an appropriate water flow rate or are simply too weak.
If your filter isn’t strong enough for the capacity of your tank or the filter suddenly stops working, it won’t be able to clean your tank water effectively. This can have a major impact on the health of your fish and cause losses that could otherwise be prevented.
To make sure your tank’s inhabitants stay happy and healthy, I’ve reviewed a range of filters that are appropriate for a 125 gallon tank.
After considering all the options our top picks were…
Review Summary
Out of all the filters I’ve looked at, this one is my top recommendation for most large tanks.
Aquatop CF Series 500UV Canister Filter
One of the best features about this device is that a UV sterilizer is built into it. UV sterilizers keep your water crystal clear and help remove algae spores or harmful bacteria.
Best All-Rounder: Aquatop CF Series 500UV Canister Filter
With a fluid rate of 525 gallons per hour, this unit is a great option for tanks up to 130 gallons. It’s quiet in operation and includes large media baskets that contain a range of media. There’s also a UV sterilizer is built into the system to keep your tank crystal clear.
MarineLand Penguin 350 Bio-Wheel Power Filter
The unit uses filter media cartridges for simplicity, making it a good pick for aquarists new to fishkeeping.
Best on a Budget: MarineLand Penguin 350 Bio-Wheel Power Filter
This filter can clean your tank efficiently without being too high in price.
If you need an affordable filter for your tank, then the MarineLand power filter is a solid choice. It offers a good amount of filtration and uses filter media cartridges for convenience.
Fluval FX4 High Performance Canister Filter
The large filter is self-starting thanks to its Smart Pump. This feature constantly monitors and optimizes the performance of the pump. It also automatically releases trapped air every 12 hours to improve the filter’s efficiency.
Editor’s Choice: Fluval FX4 High Performance Canister Filter
My personal favorite tank for a big setup. It’s a little costlier than the other products, but is extremely high quality.
This large filter is a good investment for a big tank due to how powerful it is. It has a fluid rate of 700 GPH and includes a lot of impressive features. These include large filter media baskets, an adjustable water flow, and a Smart Pump to make installation and cleaning easy.
How to Choose the Right Filter
When choosing the right aquarium filter for you, there are important factors you need to keep in mind. These include your tank size, setup, and tank’s inhabitants.
A higher fluid rate than what’s recommended for your tank volume might also be necessary if you own fish with big bioloads…
Your filter needs to have an adequate flow rate for your aquarium in order to clean it efficiently. A higher fluid rate than what’s recommended for your tank volume might also be necessary if you own fish with big bioloads, like some tang species.
UV Sterilizers
In addition to this, if you own a reef tank or outdoor pond, then you might need a filter that has a UV sterilizer built into it. A UV sterilizer helps sterilize your tank and reduce algae outbreaks.
The type of tank you own also comes into play as some filters are better suited to specific setups. For example, if you have a nursery tank or invertebrate-only tank, then a filter with gentle filtration is a good idea.
Functions of a Filter System
An aquarium filter removes uneaten food, waste, and other bits of debris from your water. Clean water is crucial for the health of your fish and ensuring their happiness. Without a filter, your tank water will become dirty very quickly and contain high levels of ammonia and nitrite.
Without a filter, your tank water will become dirty very quickly and contain high levels of ammonia and nitrite…
When ammonia or nitrite is present in your tank, even in small traces, it can be deadly. Both are caused by the build-up of decaying organisms like waste and leftover food. This is why you need a filter in your tank.
NOTE
Not only does a filter clean and purify your tank water, but it also adds water movement to your tank so your fish can breathe.
Types of Filters
There are a few different types of filters available for your aquarium, so it can be a bit confusing when it comes to deciding on the right one for your fish tank. All filters are designed to clean your tank water, but some varieties are better suited to certain setups.
Undergravel Filters
Undergravel filters are placed under the substrate. They suck up water via uplift tubes and are normally paired with a water pump, powerhead or an airstone and air pump.
TIP
This type of filter can cause detritus and hydrogen sulfide to build-up, so regular cleaning of your substrate is vital.
Wet/Dry Filters
Also known as a trickle filter, a wet/dry filter pumps tank water through a drip plate or rotating arm. The water is then pressed through biological material in the filter chamber. Lastly, the water is deposited back into the fish tank either directly or via a sump.
TIP
Wet/dry filters are a good option for saltwater aquariums or tanks with a lot of aeration.
Canister Filters
A canister filter is a popular choice in 40+ gallon fish tanks. They can be a bit more costly than other types of filters.
Filters like these are great if you own fish with strong filtration requirements like triggers or groupers.
Canister filters suck up water using a lift tube and pump it into an external filter chamber. Here, the water is pressed through filter media before being deposited back into the aquarium via a tube.
Internal Filters
For fish tanks under 20 gallons, an internal filter is a popular selection. They go directly in your tank water. Most internal filters are used with an airline and air pump.
Hang On Back/Power Filters
Hang on back (HOB)/power filters are placed on the back of your aquarium. They suck up tank water through a siphon tube and press it through filter media in the filter chamber.
Air-Driven/Sponge Filters
Air-driven/sponge filters are powered by an air pump, power head, or a second filter. They are ideal for aquariums with small fish, fry (baby fish), invertebrates, or sick fish as they provide gentle filtration. Unfortunately, air-driven filters don’t offer chemical filtration.
What is the Best Filter Type for a 100-125 Gallon Tank?
Choosing a filter for your tank is mostly down to personal preference, but most aquarists with an aquarium over 40 gallons use a canister filter. Canister filters are a fantastic option for large fish tanks as they are extremely powerful and can clean your tank water effectively.
Water Flow Rate
To properly clean your tank water, your filter needs to have a suitable water flow rate for the volume of your tank. As a rule, your filter should be able to clean at least four times the volume of your aquarium per hour.
For example, a 125 gallon aquarium filter should have a fluid rate of at least 500 GPH (gallons per hour).
Filtration Technology
There are three types of filtration you should use in your tank: chemical, biological, and mechanical. Mechanical filtration gets rid of excess food, waste, and other debris from your tank. Biological filtration is the process of beneficial bacteria converting ammonia into nitrite and nitrite into nitrate.
NOTE
Chemical filtration is optional, but it’s still recommended as it removes particulates from your water to help purify it.
Can You Use Two Filters in a Tank?
You can use two filters in your tank, but it’s not normally necessary. A single filter is more than capable of cleaning your tank water as long as it has a suitable fluid rate for the size of your tank.
If your filter has a low flow rate, then you can use a second filter to make up the extra gallons per hour…
If your filter has a low flow rate, then you can use a second filter to make up the extra gallons per hour. For example, if your main filter in your 100 gallon tank has a flow rate of 350 GPH, you should use a second filter with a flow rate of at least 50 GPH.
NOTE
Some aquarists use more than one filter in their tank for backup in case their main one breaks or for fish with particularly high bioloads. Alternatively, some fishkeepers use a second filter alongside an air-driven filter.
Can You Over Filter a Tank?
You can’t over filter a fish tank, so it’s a good idea to use a filter with the highest GPH you can afford. The only possible drawback of using a powerful or second filter is that the water movement could be a little excessive for the size of your tank. This might result in your tank’s inhabitants being a bit stressed out.
Large Aquarium Filter Reviews
Aquatop CF Series 500UV Canister Filter
One of the best features about this device is that a UV sterilizer is built into it. UV sterilizers keep your water crystal clear and help remove algae spores or harmful bacteria.
Best All-Rounder: Aquatop CF Series 500UV Canister Filter
This canister filter is my overall recommendation for up to a 130 gallon tank as it has a fluid rate of 525 gallons per hour. This provides your tank with ample mechanical and biological filtration
enough room to add extra filter media for a new tank to jumpstart the cycling process…
You get three huge filter media baskets with the unit, which allows you full customization of the type of media you use. There’s also enough room to add extra filter media for a new tank to jumpstart the cycling process.
Setup
Assembly-wise, the filter is fairly simple to install as it is self-priming. It comes with an assortment of filter media, including three fine filter pads and a single coarse sponge. This is handy as you don’t need to purchase separate media other than chemical media.
One of the best features about this device is that a UV sterilizer is built into it…
One of the best features of this device is that a UV sterilizer is built into it. Aquarium UV sterilizers keep your water crystal clear and help remove algae spores or harmful bacteria.
Low Noise
Another great aspect of the unit is its quiet operation. A lot of large filters designed for a big tank can be a bit noisy, so I like that this one doesn’t suffer from loudness.
However, the unit is prone to leaking as some parts like the rim connector are not very durable. Additionally, the device can decrease in effectiveness over time.
Specs
- Size: 18” x 11” x 12”
- Weight: 19.6 lbs
- Fluid Rate: 525 GPH
- Recommended Tank Size: Up to 130 gallons
Pros
- Large media baskets
- Includes some media
- Self-priming
- Built-in UV sterilizer
Cons
- Durability issues
- Can loses efficiency over time
MarineLand Penguin 350 Bio-Wheel Power Filter
The unit uses filter media cartridges for simplicity, making it a good pick for aquarists new to fishkeeping.
Best on a Budget: MarineLand Penguin 350 Bio-Wheel Power Filter
Despite its low price, this filter is a decent option for a big tank as it offers a good amount of chemical, mechanical, and biological filtration.
Despite its low price, this filter is a decent option for a big tank…
In tanks over 100 gallons, you’ll need to use an additional filter with MarineLand’s unit as it only has a fluid rate of 350 gallons per hour. However, even purchasing two of these filters still won’t cost an arm and a leg!
Media Cartridge
The unit uses filter media cartridges for simplicity, making it a good pick for aquarists new to fishkeeping. Some cartridges are included with the unit, which is a nice extra.
MarineLand’s power filter uses a rotating bio-wheel that provides excellent filtration…
MarineLand’s power filter uses a rotating bio-wheel that provides excellent filtration. It also has a two-piece vented cover to reduce noise during operation, as well as adjustable mid-level intake strainers. This improves water circulation in your fish tank.
Unfortunately, this power filter is not the best in terms of quality as it is prone to breaking fairly quickly. The impeller can also develop a grinding noise over time, which can cause the unit to be a bit loud.
Specs
- Size: 15.2” x 6.1” x 8”
- Weight: 3.53 lbs
- Weight: 3.53 lbs
- Recommended Tank Size: Up to 75 gallons
Pros
- Includes filter media cartridges
- Relatively quiet
- Good amount of filtration
Cons
- Can break prematurely
- Can develop a grinding noise
Fluval FX4 High Performance Canister Filter
The large filter is self-starting thanks to its Smart Pump. This feature constantly monitors and optimizes the performance of the pump. It also automatically releases trapped air every 12 hours to improve the filter’s efficiency
Editor’s Choice: Fluval FX4 High Performance Canister Filter
With a flow rate of 700 gallons per hour, this filter from Fluval is an excellent choice for large tanks. It has removable and large filter media baskets that can hold up to a gallon of media.
The large filter is self-starting thanks to its Smart Pump…
The large filter is self-starting thanks to its Smart Pump. This feature constantly monitors and optimizes the performance of the pump. It also automatically releases trapped air every 12 hours to improve the filter’s efficiency
Media Included
You get chemical, biological, and mechanical media with the unit for added convenience. I appreciate this as it means you don’t need to go out of your way to purchase separate filter media.
NOTE
Despite being very powerful, the unit has a relatively compact and tall design. It should easily fit under most aquarium stands.
Low Noise
The filter is relatively quiet in operation due to the rubber feet located on the bottom of the unit, which is a feature I appreciate. I also like that the filter has multi-directional output nozzles that can be adjusted so you can change the flow rate.
Another great aspect of the Fluval FX4 filter is how simple it makes performing water changes in your fish tank…
Another great aspect of the Fluval FX4 filter is how simple it makes performing water changes in your fish tank. All you need to do is attach the included hosing to the output of the filter and then let the Smart Pump take over.
The only downside of this filter is that some parts like the rim connector are not very durable, so they might need to be replaced regularly.
Specs
- Size: 15.6” x 15.6” x 17.7”
- Weight: 18 lbs
- Flow Rate: 700 GPH
- Recommended Tank Size: Up to 250 gallons
Pros
- Adjustable flow rate
- Large filter media baskets filled with media
- Makes water changes simple
- Compact and tall design
Cons
- Some parts are not as durable as others
AquaClear 110 Filtration System
The design of the device allows for superior contact time with filter media, which improves its filtering capabilities.
AquaClear 110 Filtration System
Featuring an energy efficient pump, the AquaClear 110 is suitable for tanks over 100 gallons as it has a fluid rate of 500 GPH. The design of the device allows for superior contact time with filter media, which improves its filtering capabilities.
The design of the device allows for superior contact time with filter media…
You get an array of medium included with the unit, such as a BioMax insert, foam filter insert, and activated carbon. All of these help pave your way to a crystal clear enclosure.
Setting up this filtration system is quite simple and stress-free…
Setting up this filtration system is quite simple and stress-free. It’s a hang-on-back unit, so it’s easier to maintain and assemble than canister filters.
Despite its positives, this filtration system can get clogged easily and have some durability issues. These include noisy operation and a short lifespan.
Specs
- Size: 17.4” x 12.5” x 11”
- Weight: 6.6 lbs
- Fluid Rate: 500 GPH
- Recommended Tank Size: Over 100 gallons
Pros
- Design improves effectiveness of filter medium
- Easy to set up
- Comes with media
Cons
- Can be a bit noisy
- Can have durability issues
Penn Plax Cascade 1500 Canister Filter
This canister filtering unit from Penn Plax is another solid choice for your tank. While the fluid rate of the unit is only 350 GPH, it would work well alongside an additional filtration system.
Penn Plax Cascade 1500 Canister Filter
This canister filtering unit from Penn Plax is another solid choice for your tank. While the fluid rate of the unit is only 350 GPH, it would work well alongside an additional filtration system.
There is a smaller version of this filter that works great as a 75-gallon aquarium filter so keep that in mind if you have a smaller tank.
Large Media Basket
It sports large media baskets that are filled with a coarse sponge and floss pad. There’s also enough space to add more media, too
The fluid rate of the unit can be adjusted…
The fluid rate of the unit can be adjusted, allowing you to select a slow or fast current. During operation, the device is fairly quiet, this makes it a good option if your tank is located in your bedroom.
Although the device is quite easy to clean and install, it can sometimes suffer from a couple of maintenance problems. For one, the unit can be time-consuming to clean. And secondly, the device’s tubes can leak when they are disconnected.
Specs
- Size: 20.5” x 12” x 11”
- Weight: 15 lbs
- Flow Rate: 350 GPH
- Recommended Tank Size: Up to 75 gallons
Pros
- Includes media
- Large media baskets
- Quiet operations
Cons
- Can be time-consuming to clean
- Ill-fitting tubes
Summary
Here’s a quick recap of all our top picks…
Best All-Rounder
After looking at a variety of filters, I think the best 125 gallon aquarium filter is the Aquatop CF Series 500UV Canister Filter. It has a fluid rate of 525 gallons per hour, making it suitable for tanks up to 130 gallons.
The unit comes with three large media baskets, three filter pads, and a coarse sponge to provide both mechanical and biological filtration for your aquarium. I like that the canister filter is quiet in operation and has a UV sterilizer built into it. This is useful for eliminating algae and removing harmful bacteria.
Best on a Budget
If Aquatop’s 500UV filter doesn’t seem right for you, then either MarineLand Penguin 350 Bio-Wheel Power Filter or Fluval FX4 High Performance Canister Filter are also worth considering. The former is very affordable but has a fairly low fluid rate, so it needs to be used alongside another filter. On the plus side, the unit includes media cartridges and has an adjustable fluid rate.
Editor’s Choice
My favorite 125 gallon aquarium filter is the Fluval FX4. It has a fluid rate of 750 GPH, so it’s perfect for up to a 250 gallon fish tank. For the most part, it’s durable and hardy, making it a worthwhile investment.
